Recently, HDMI (High Definition Multimedia Interface), one of the digital audio/video (hereinafter: AV) input/output interface standards for home electric appliances and AV appliances, becomes widespread. When HDMI cable is used for connecting a video source, such as a DVD player or a Setup-box, to a television, video data from the video source to the television can be transmitted at a maximum transmission rate of about 3 Gbps. Further, HDMI cable is not limited to be used for the transmission of video data from the video source to the television; HDMI cable can also be used for transmission of an appliance controlling command via which the television controls the video source.
Recently, WirelessHD has defined as a standard for using wireless technology to transmit AV contents such as video data and audio data, and the overview of the standard was published (http://www.wirelesshd.org/WirelessHD_Full_Overview—071009.pdf).
WirelessHD employs millimeter radio wave (Hereinafter: millimeter wave), which uses 60 GHz band as a frequency band. A frequency band including 60 GHz band, which is for example a frequency band of 7 GHz bandwidth from 59 GHz to 66 GHz in Japan, can be freely used without any license. Since such broad bandwidth can be used in millimeter wave, the scheme is suitable for wireless video data transmission which requires high data transmission rate.
The overview of WirelessHD also mentions that signals received via a HDMI cable from an appliance that supports HDMI are transmitted through a wireless connection.
However, the overview of WirelessHD does not mention a detailed transmission scheme regarding wireless transmission of HDMI signals using WirelessHD that are received via the HDMI cable from the appliance that supports HDMI.
Since wavelength of millimeter wave signal is short, millimeter wave signal has high straightness and thus when transmission path is blocked by an obstacle such as a human body, the communication is easily disrupted. Therefore, in case millimeter wave signal is used for wireless transmission of real time data such as AV data, above characteristics should be considered when a system architecture is designed.
One aspect of the present invention provides a transmission method that supports full-duplex wireless communication using signals with short wavelength such as millimeter wave signals.